The present invention relates generally to a method for extracting carbon dioxide from of an internal combustion engine exhaust and automatically adding the extracted carbon dioxide to a vapor compression system for use as a refrigerant.
Chlorine based refrigerants have been phased out in most of the world due to a possible detrimental effect on the environment. Hydrofluoro carbons (HFCs) have been used as replacement refrigerants, but these refrigerants may still be detrimental to the environment.
“Natural” refrigerants, such as carbon dioxide and propane, have been proposed as replacement fluids. Carbon dioxide can be used as a refrigerant in automotive air conditioning systems and other heating and cooling applications. Carbon dioxide has a low critical point, which causes most air conditioning systems to run transcritically, or partially above the critical point, under most conditions.
The possibility of refrigerant leakage increases when a vapor compression system runs with carbon dioxide due to the high operating pressure. Carbon dioxide systems generally have a high volumetric capacity, and therefore carbon dioxide vapor compression systems have less charge than a system using a conventional refrigerant. Therefore, a refrigerant leak in a carbon dioxide system has a greater influence on the system performance than a leak in a system using a conventional refrigerant. When charge leaks, additional refrigerant must be added to the system. Traditionally, the additional refrigerant is added manually. However, adding additional charge to a vapor compression system is both costly and labor intensive.
Thus, it is desirable to provide a method for automatically adding carbon dioxide refrigerant to a vapor compression system that is not labor intensive and costly, as well as overcoming the other above-mentioned deficiencies of the prior art.